Security devices

ABSTRACT

An electrical switch for use in connection with, for example, courtesy lights in automobiles, truck lights and refrigerator lights. The switch has three members, two of which are relatively movable against a biassing force to make and/or break an electric circuit supplying, for example, the courtesy light. The third member has an interference fit within a bore in one of the other two members and forms an adjustable extension thereof constituting an abutment whereby the switch is operable. When fitting the switch to a door, the third member is fitted loosely in the bore so that when the door is closed for the first time, the rod is forced through the bore to a position wherein the door is closed and the switch is operated. The interference fit retains the rod in this position.

ilited States Patent 1 1 Palman June 12, 1973 SECURITY DEVICES [76] Inventor: Leonard Palman, 5 Windsor Close,

Hendon Lane, London N .3 England [22] Filed: Dec. 29, 1971 21 Appl. No.: 213,705

52 us. (:1. 200/44 51 1111. C1. ..H01h 27/00 [58] Field of Search 200/42, 44, 153 LA,

ZOO/6159,11, 11 A, 11 B, 11c

[56] References Cited UNITED STATES PATENTS 3,651,288 3/1972 Cryer 200/44 Primary ExaminerHerman J. Hohauser Attorney-Harold R. Woodard [57] ABSTRACT An electrical switch for use in connection with, for example, courtesy lights in automobiles, truck lights and refrigerator lights. The switch has three members, two of which are relatively movable against a biassing force to make and/or break an electric circuit supplying, for example, the courtesy light. The third member has an interference fit within a bore in one of the other two members and forms an adjustable extension thereof constituting an abutment whereby the switch is operable. When fitting the switch to a door, the third member is fitted loosely in the bore so that when the door is closed for the first time, the rod is forced through the bore to a position wherein the door is closed and the switch is operated. The interference fit retains the rod in this position.

2 Claims, 3 Drawing Figures SECURITY DEVICES BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a security lock and more particularly to a combined lock and key switch for use on vehicles.

2. Description of the Prior Art It is known to produce, in one unit, a security lock incorporating a conventional key operated barrel lock and a switch assembly used to lock, for example, a vehicle door and to simultaneously set an alarm system to an operable condition. However, this construction is disadvantageous because it is necessary to replace the whole assembly if only a single part is faulty. It is often necessary to replace a security lock because the switch section has become corroded or faulty due to the penetration of water and dirt. Thus, in order to replace an inexpensive switch component, the relatively expensive key-operated lock must also be replaced.

According to this invention, a security lock comprises a key operated lock and an electric switch wherein the electrical switch includes a housing and a boss adapted to be removably mounted on a shaft which extends from the lock and is turnable by means of a key to thereby turn the boss within the housing and cause contact between a pair of electrical terminals to be made or broken.

Preferably the housing and the key operated lock are adapted for mutual location to prevent relative angular displacement therebetween and, further, the boss and the shaft are also adapted for mutual location so as to constrain the boss to turn with the shaft.

SUMMARY OF THE INVENTION One embodiment of the present invention is a security lock comprising a key operated lock and an electric switch wherein the electric switch includes a housing and a boss adapted to be removably mounted on a shaft which extends from the lock and is turnable by means ofa key to thereby turn the boss within the housing and cause contact between a pair of electrical terminals to be made or broken.

BRIEF DESCRIPTION OF THE DRAWING The invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 shows a cross-section elevation of a security lock;

FIG. 2 is a cross-section on A-A of FIG. 1;

FIG. 3 shows a circuit diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the circular barrel 8 of a lock 10 mounted on a panel 12 and secured thereto by means of a nut 14. The lock is of a known type and therefore the barrel is not drawn in cross-section. The actuating shaft 16 extends for some distance beyond the barrel 8 and on that shaft extension is mounted a boss 18. The boss is constrained, by virtue of the shape of the shaft and the hole in the boss through which the shaft extends, to turn with the shaft within a housing 20 surrounding the boss. The housing 20 is located against the barrel 8 in such a manner that it is prevented from rotating with the boss by, for example, cooperating flat surfaces. A cover 24 is attached to the end of the shaft 16 by means of a screw 26 and is therefore constrained to turn with the shaft. In FIG. 1 the cover 24 is aligned with the end of the housing 20.

The shaft 16 may assume one of two positions when the key operated lock is turned.

FIG. 2 is a cross-sectional view of A-A of FIG. 1 and shows clearly the shaft 16 and the shaped hole 28 in the boss 18 referred to above. An electrically conducting contact plate 30 is mounted in a slot 32, formed in the boss parallel to a diameter, the ends of which are bent such that the two portions of the plate 34 lie on the same diametral line and are equidistant from the center line of the shaft.

Four contact strips 36 are attached to and are equally spaced around the internal circumferential surface of the housing 20 in such a way that the plate 30 makes contact between two of those contact strips when the shaft is in one position and that, when the key is turned the plate makes contact between the two remaining diametrically opposite strips.

The housing and the boss are each formed from an electrically insulating material.

It has been stated above that a security lock may be used to lock a door and simultaneously to set an alarm system to the operable condition. However, by using four rather than two terminals it is possible to take a further security precaution. For example, by connecting the two terminals, not used in the alarm system, into the ignition circuit it would be possible to achieve the following two sets of conditions:

A. Door unlocked Alarm system isolated Ignition operative. B. Door locked Alarm system operative Ignition isolated.

The letters A and 8 correspond to the terminal pairs so marked in FIG. 3 which is a simplified circuit diagram.

The mechanical functions of the lock are performed in the normal way, but the housing is so positioned that in the unlocked position the plate 30 makes contact between the terminal pair A thereby setting the ignition circuit and neutralizing the alarm circuit. Conversely, in the locked position the plate makes contact between the terminal pair B as shown in FIG. 3, thereby setting the alarm system and isolating the ignition circuit.

The invention claimed is:

l. A security lock comprising a key operated lock and an electric switch wherein the lock has an extending shaft and the switch comprises a hollow cylindrical housing attached to the key operated lock so as to prevent relative angular displacement thereof, a boss removably mounted on and for angular displacement with the shaft which extends from the lock and is turnable by means of a key, a bridging electrical contact member carried by the boss and extending beyond the margin of the boss, one or more pairs of terminals adapted to be engaged by said bridging member and arranged around the internal circumferential surface of the housing and extending axially of the shaft through an open end of the housing remote from the key operated lock and through slots in an annular cover, said cover being attached to the open end of the housing and having an internal diameter less than the external diameter of the boss, and means attached to the end of the shaft retaining the boss on the shaft within the houssaid boss, the curved extending ends of said member engaging said terminals at selected positions of said shaft. 

1. A security lock comprising a key operated lock and an electric switch wherein the lock has an extending shaft and the switch comprises a hollow cylindrical housing attached to the key operated lock so as to prevent relative angular displacement thereof, a boss removably mounted on and for angular displacement with the shaft which extends from the lock and is turnable by means of a key, a bridging electrical contact member carried by the boss and extending beyond the margin of the boss, one or more pairs of terminals adapted to be engaged by said bridging member and arranged around the internal circumferential surface of the housing and extending axially of the shaft through an open end of the housing remote from the key operated lock and through slots in an annular cover, said cover being attached to the open end of the housing and having an internal diameter less than the external diameter of the boss, and means attached to the end of the shaft retaining the boss on the shaft within the housing, whereby when the key is turned contact between a pair of the terminals is made or broken.
 2. A security lock as claimed in claim 1 in which said bridging member is substantially C-shaped with its central portion being received in a chordal slot formed in said boss, the curved extending ends of said member engaging said terminals at selected positions of said shaft. 